Cannula



FIG. 1 is a perspective view of a cannula showing my new design;

FIG. 2 is a front plan view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design of a cannula, as shown and described. 